IMMUNOLOGY - Ocular Clinical Immunology

Question 1

What is the main immunoglobulin in human tears?

Answer 1

IgA

Question 2

What are the DNA viruses (7)

Answer 2

1. Adenovirus
2. Herpes SIMPLEX virus
3. Varicella ZOSTER virus
4. Epistein Barr virus
5. Cytomegalovirus
6. Molluscum contagiosum virus
7. Vaccinia and variola virus

Question 3

What are RNA viruses? (5)

Answer 3

1. Picorna virus
2. Paramyxo virus
3. Toga virus
4. Flavi virus
5. Filo virus

Question 4

Which virus is the most common cause of conjunctivitis? Which subtype?

Answer 4

Adenovirus (DNA) –> mostly belong to subgroup D (A-F classification) –> usually type 8, 19 and 37 –> type 8 is classic cause of EKC

Question 5

What is the systemic effect of leukotrienes? (3)

Answer 5

1. Bronchoconstriction
2. Vasoconstriction
3. Increase vascular permeability
   –> involved in allergic reactions and inflammation

Question 6

What is the main complement implicated in AMD?

Answer 6

Factor H. This checks complement cascade at C3 and C5 induction.

Question 7

Which cells are associated with sympathetic ophthalmia?

Answer 7

TH1 lymphocytes (CD4)

Question 8

Which cells are associated with parasite induced granulomas?

Answer 8

TH2 lymphocytes (CD4)

Question 9

What type of immune cell is associated with birdshot choroidoretinopathy?

Answer 9

TH17 (CD4)

Question 10

What do tears contain to fight off bacteria and which type of bacteria are more effective against?

Answer 10

Lysozymes - more effective against gram-negative bacteria

Question 11

What happens in steven johnson’s syndrome? What type? What immunodeficiencies occur?

Answer 11

Type 4 hypersensiivity reaction caused by cytotoxic reaction against keratinocytes that express foreign antigens.

1. Granulysin secretion by cytotoxic T cells
2. Drug-specific CD8+ expansion and infiltration into dermoepidermal junction
3. TNF protein activation induces cell apoptosis
4. Epithelial damage causing sloughing of mucous membranes
   5.

Question 12

What is MALT? Where is it present and what predominant antibody does it produce? What happens after antigen presentation?

Answer 12

Mucosal Associated Lymphoid Tissues –> collection of subepithelial lymphocytes, APCs (dendritic cells) and lymphoid tissue not contained within a capsule.

Present on mucosal surfaces (such as conjunctiva and ocular adnexal glands).

Predominant immunoglobulin produced is IgA. Rarely, lymphoma arises from this tissue.

Antigen exposure stimulates IgA at all mucosal surfaces. B-cells and T-cells express homing receptors for addressins which direct movement of cells to various mucosal sites

Question 13

What is the therapeutic use of Interferon Alpha, Interferon beta, Interferon gamma

Answer 13

Alpha: Viruses (HBV, HCV, HHV-8 (Kaposi Sarcoma) , HTLV-2 (B cell leukaemia)

Beta: Multiple sclerosis

Gamma: chronic granulomatous disease

Question 14

Corneal graft rejection is what type of hypersensitivity reaction?

Answer 14

Type 4.

Question 15

Which antigen is associated with cancer-associated retinopathy syndrome?

Answer 15

Recoverin - calcium-binding protein which inhibits rhodopsin phosphoylation

Question 16

What antigen is involved in leber congenital amaneurosis and retinitis pigmentosa?

Answer 16

RPE65 - plays role in vitamin A metabolism

Question 17

Which antigen is found in VKH syndrome?

Answer 17

Tyrosinase - found in melanocytes.

Question 18

Where are APCs found in ocular tissues? What quality do normal APCs have that ocular APCs don’t have?

Answer 18

Limbus, ciliary & iris epithelium, ciliary muscle, processes and TM

Dendritic cells found at ora serrata in neural retina and in connective tissue aroudn choriocapillaries

Ocular APCs cannot activate T cells like conventional APCs

Question 19

What components are contained in the aqueous?

What is its main function (2)

Answer 19

BACTERIOSTATIC PROPERTIES
1. Complement
2. Immunoglobulin
3. Defensins
4. Beta-Lysin

Immunosuppress: inhibit T-cell proliferation (via TGF-beta), inhibits lymphokine production and suppresses macrophage and APC activityto allow for ocular immune privilege

Question 20

What is ocular immune privilege? What are its components? (4)

Answer 20

Protects ocular structures from potentially damaging immune-mediated inflammation

1. Blood-ocular barrier
2. Lack of lymphatics to the eye
3. Soluble immune modulatory mediators in aqueous
4. Unique tolerance promoting APCs

Question 21

What is the process of corneal angiogenesis? What does it respond to?

Answer 21

Response to inflammation promoted by fibrin and its degradation products.

1. Latent - vasodilation, vascular permeability of neighbouring vessels, stromal oedema
2. Endothelial activation (24 hours), the endothelium retracts and nucleoli enlarge
3. Endothelial basement membrane/basal lamina broken down by plasminogen activator which is produced by fibroblasts, macrophages and others
4. Vascular sprouting - sprouts from post-capillary venules and capillaries
5. Vascular maturation - deposition of ECM and laminin and basal lamina/basement membrane formation

Question 22

Which immunomodulators are contributory to ocular immune privilege?

Answer 22

TGF-B, IL-10 (immunosuppressive)
NK T cells mediate their activity